Optically active bis(oxazolinyl)phenyl metal complexes as multipotent catalysts

Abstract

The bis(oxazolinyl)phenyl (abbreviated as phebox) ligand, which consists of two chiral oxazolines and a benzene backbone, is one of the most useful scaffolds for the construction of chiral NCN pincer complexes. The resulting phebox metal complexes can effectively deliver a C 2-symmetric environment around the active metal center. Currently, various transition metals in the range of early to late metals have been introduced by cyclometalation and transmetalation reactions to construct phebox metal complexes. Among them, the phebox Rh and Ru complexes have been extensively investigated as molecular catalysts for asymmetric catalytic reactions. High efficiency and selectivity were obtained in functionalization reactions, such as hydrosilylation, conjugate reduction, and borylation, and carbon-carbon bond formation reactions, such as reductive aldol reaction and alkynylation. The phebox complex is a good representative multipotent catalyst. Graphical Abstract: © 2013 Springer-Verlag Berlin Heidelberg.